Partial liquid ventilation with surfactant: effects on gas exchange and lung pathology in surfactant-depleted piglets

Objective: To evaluate the effects of 24 h partial liquid ventilation (PLV) with and without surfactant (S) treatment on gas exchange and lung injury in a newborn animal model of S deficiency. Design : A prospective, controlled, in vivo animal laboratory study. Setting: Research laboratory in a university setting. Subjects: Twenty-four pathogen-free, male piglets (mean weight 1.9 kg, age 1-3 days). Interventions: The animals were randomised in four groups: PLV with FC-77 c ombined with conventional ventilation (PLV/CV) versus S + PLV/CV and PLV co mbined with high frequency oscillatory ventilation (PLV/HFOV) versus S + PL V/HFOV. The piglets were anaesthetised, intubated and instrumented with vas cular catheters. Thirty minutes after lung injury had been induced with rep eated saline lavage, S animals received natural S, Thirty minutes after sur factant substitution PLV with FC-77 was started. The oxygenation index (OI) , PaO2/FIO2 ratio, PaCO2 and the ventilatory efficacy index were determined before and during PLV. After 24 h the lungs were removed for histopatholog ical examination. Measurements and main results: Within 60 min after the initiation of PLV, a ll animals demonstrated improvements of the OI and PaO2/FIO2 ratio compared to the values after lung injury. However, at 18 and 24 h of PLV, the OI an d PaO2/FIO2 ratio were significantly worse in the S + PLV/CV and S + PLV/HF OV groups compared to the groups without S. PaCO2 was higher at 18 and 24 h when S was used in PLV/HFOV (p < 0.05). A semi-quantitative lung injury sc ore revealed most severe lung damage in the S + PLV/HFOV group. Conclusion: The combination of S and PLV with FC-77 led to an impaired gas exchange and did not further protect the animal from lung injury.